Gaara's father can use Magnetism Release, it's said in the Manga itself, that he combines his magnetic chakra with the sand around him leading to the creation of Gold Dust.Not that I want to get into this long argument but are you sure you are not confusing two people together?
The third Kazekage can use magnetism - yes. The fourth, for now, cannot.
The third Kazekage's son is unknown, for now. The fourth's son is Gaara.
The Kazekage shown in the last manga is the fourth, not the third. The one shown is the one we are not sure can use magnetism.
I also think some peolpe confuse the cloud ninja that Naruto owned and gaara's dad. That one can use magnetism but is fromt he cloud. Peace.
P.S Multiposting is not allowed man, it's boring when people do this and they do it just for posts and kumis, so do not do that again if you don't want to be reported by someone.